Stanford University owns 8,180 acres (32 km²), making it the second-largest university complex in the world. The main campus is bounded by El Camino Real, Stanford Avenue, Junipero Serra Boulevard and Sand Hill Road, in the center of the Santa Clara Valley on the San Francisco Peninsula.

The Stanford Quad and its original Moorish-Romanesque architecture are part of the campus plan contributed by H. H. Richardson, his successors, Shepley, Rutan and Charles Allerton Coolidge, and legendary architect Frederick Law Olmsted. Much of the first construction was destroyed by the 1906 San Francisco earthquake but the University retains the Quad, the old Chemistry Building (which is currently unoccupied) and Encina Hall (reportedly the residence of John Steinbeck during his time at Stanford). After the 1989 Loma Prieta earthquake inflicted further damage the University implemented a billion-dollar capital improvement plan to retrofit and renovate older buildings for new, up-to-date uses.

Many of the modern buildings were designed in the Spanish-colonial style common to California, with red tile roofs and white stucco exteriors, which gives the campus a uniform yet distinctly Californian look that many find aesthetically pleasing—the red tile roofs and bright blue skies common to the region are a famously complementary combination. The University has its own golf course and a seasonal lake (Lagunita), both home to the endangered California Tiger Salamander.

The off-campus Jasper Ridge Biological Preserve is a nature reserve owned by the university and used by wildlife biologists for research. Hopkins Marine Station, located in Pacific Grove, California, is a marine biology research center owned by the university since 1892.

Contemporary campus landmarks include the Stanford Quad and Memorial Church, the art museum and art gallery, the Stanford Mausoleum and the Angel of Grief, Hoover Tower, the Rodin sculpture garden, the Papua New Guinea sculpture garden, Green Library and the Dish. Frank Lloyd Wright's 1937 Hanna House, and the 1919 Lou Henry and Herbert Hoover House, are both National Historic Landmarks now on university grounds.